From 17da9943458ae93ecb272eccf2a41d3e5a001a77 Mon Sep 17 00:00:00 2001
From: Ivan Grokhotkov <ivan@espressif.com>
Date: Mon, 5 Jun 2017 11:01:26 +0800
Subject: [PATCH] esp_event_send: check if the event loop is initialized

Fixes https://github.com/espressif/esp-idf/issues/668
---
 components/esp32/event_loop.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/components/esp32/event_loop.c b/components/esp32/event_loop.c
index 4b6e21fe0..a8d41e378 100644
--- a/components/esp32/event_loop.c
+++ b/components/esp32/event_loop.c
@@ -72,6 +72,10 @@ system_event_cb_t esp_event_loop_set_cb(system_event_cb_t cb, void *ctx)
 
 esp_err_t esp_event_send(system_event_t *event)
 {
+    if (s_event_queue == NULL) {
+        ESP_LOGE(TAG, "Event loop not initialized via esp_event_loop_init, but esp_event_send called");
+        return ESP_ERR_INVALID_STATE;
+    }
     portBASE_TYPE ret = xQueueSendToBack(s_event_queue, event, 0);
     if (ret != pdPASS) {
         if (event) {